1. Field of the Invention
The present invention relates to an image generating technique and, more particularly, to an image generating method and image generating apparatus operated on the basis of combining a plurality of images.
2. Description of the Related Art
Techniques for displaying a digitized map image on a display apparatus have been known in the form of software for PCs or Internet services. Map images are generally prepared for a plurality of discrete scales so that one of the plurality of map images is displayed at a desired point of time.
When a scale is changed and a map image displayed on a display apparatus is changed accordingly, a user may lose sight of an object that the user had paid attention to or it may take a substantial time for the user to understand the currently displayed area. From these points of view, when the scale of a map image is changed, the displayed map image is desirably switched from one to another smoothly.
Smooth switching between displayed images is required not only in the case of digitized map images but also in the case of drawing a landscape in applications such as games. In games, three-dimensional data of objects are prepared in advance. An image is re-rendered in accordance with a change in the magnification of image to be displayed and the position of point of view, so that smooth image changing or switching can be realized. The volume of calculation required for the re-rendering may be significantly increased depending on the degree of movement of point of view, the number of objects to be displayed and the degree of complexity thereof. Further, there may arise a problem about the size of capacity of memory for storing three-dimensional data of a large number of objects. Accordingly, for CG images in general, including those used for games, smooth changing between images requires further technical improvement.